logger.go

Documentation: github.com/go-kivik/kivik/v4/x/kivikd/logger

     1  // Licensed under the Apache License, Version 2.0 (the "License"); you may not
     2  // use this file except in compliance with the License. You may obtain a copy of
     3  // the License at
     4  //
     5  //  http://www.apache.org/licenses/LICENSE-2.0
     6  //
     7  // Unless required by applicable law or agreed to in writing, software
     8  // distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
     9  // WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
    10  // License for the specific language governing permissions and limitations under
    11  // the License.
    12  
    13  // Package logger defines the logger used by kivikd.
    14  package logger
    15  
    16  import (
    17  	"fmt"
    18  	"io"
    19  	"net/http"
    20  	"os"
    21  	"strings"
    22  	"time"
    23  )
    24  
    25  // RequestLogger is a request logger.
    26  type RequestLogger interface {
    27  	Log(req *http.Request, status int, fields Fields)
    28  }
    29  
    30  // Pre-defined log fields
    31  const (
    32  	FieldUsername     = "username"
    33  	FieldTimestamp    = "timestamp"
    34  	FieldElapsedTime  = "elapsed"
    35  	FieldResponseSize = "size"
    36  )
    37  
    38  // Fields is simple wrapper around logging fields.
    39  type Fields map[string]interface{}
    40  
    41  // Exists returns true if the requested key exists in the map.
    42  func (f Fields) Exists(key string) bool {
    43  	_, ok := f[key]
    44  	return ok
    45  }
    46  
    47  // Get returns the value associated with a key.
    48  func (f Fields) Get(key string) interface{} {
    49  	return f[key]
    50  }
    51  
    52  // GetString returns a value as a string, or "-"
    53  func (f Fields) GetString(key string) string {
    54  	v, ok := f[key].(string)
    55  	if ok {
    56  		return v
    57  	}
    58  	return "-"
    59  }
    60  
    61  // GetDuration returns a value as a time.Duration
    62  func (f Fields) GetDuration(key string) time.Duration {
    63  	v, _ := f[key].(time.Duration)
    64  	return v
    65  }
    66  
    67  // GetTime returns a value as a timestamp.
    68  func (f Fields) GetTime(key string) time.Time {
    69  	v, _ := f[key].(time.Time)
    70  	return v
    71  }
    72  
    73  // GetInt returns a value as an int.
    74  func (f Fields) GetInt(key string) int {
    75  	v, _ := f[key].(int)
    76  	return v
    77  }
    78  
    79  type logger struct {
    80  	w io.Writer
    81  }
    82  
    83  var _ RequestLogger = &logger{}
    84  
    85  // New returns a new RequestLogger that writes apache-style logs to an io.Writer.
    86  func New(w io.Writer) RequestLogger {
    87  	return &logger{w}
    88  }
    89  
    90  // DefaultLogger logs to stderr.
    91  var DefaultLogger = New(os.Stderr)
    92  
    93  func (l *logger) Log(req *http.Request, status int, fields Fields) {
    94  	_, _ = fmt.Fprintf(l.w, `%s %s [%s] (%s) "%s %s %s" %d %d "%s" "%s"%c`,
    95  		req.RemoteAddr[0:strings.LastIndex(req.RemoteAddr, ":")],
    96  		fields.GetString(FieldUsername),
    97  		fields.GetTime(FieldTimestamp).Format("2006-01-02 15:04:05Z07:00"),
    98  		fields.GetDuration(FieldElapsedTime).String(),
    99  		req.Method,
   100  		req.URL.String(),
   101  		req.Proto,
   102  		status,
   103  		fields.GetInt(FieldResponseSize),
   104  		req.Header.Get("Referer"),
   105  		req.Header.Get("User-Agent"),
   106  		'\n',
   107  	)
   108  }
   109
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